warn against (something)(redirected from warn someone against)
warn against (something)
To caution (someone) not to do something that is dangerous or risky. A noun or pronoun can be used between "warn" and "against." My mother always warned me against hanging out with hoodlums like you, and now I know why. Doctors are warning against spending too much time outside during this week's heatwave.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
warn someone against someone or something
to advise someone against someone, something, or doing something. We warned them all against going to the region at this time. I warned her against Gerald.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
To advise someone that something is dangerous or problematic and should be avoided: I warned them against driving without seatbelts. The doctor warns against smoking.
The American Heritage® Dictionary of Phrasal Verbs. Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.